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<title>18.22.3 CookiePolicy Objects </title>
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<h2><a name="SECTION00202230000000000000000"></a><a name="cookie-policy-objects"></a>
<br>
18.22.3 CookiePolicy Objects 
</h2>

<p>
Objects implementing the <tt class="class">CookiePolicy</tt> interface have the
following methods:

<p>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-4380' xml:id='l2h-4380' class="method">set_ok</tt></b>(</nobr></td>
  <td><var>cookie, request</var>)</td></tr></table></dt>
<dd>
Return boolean value indicating whether cookie should be accepted from server.

<p>
<var>cookie</var> is a <tt class="class">cookielib.Cookie</tt> instance.  <var>request</var> is
an object implementing the interface defined by the documentation for
<tt class="method">CookieJar.extract_cookies()</tt>.
</dl>

<p>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-4381' xml:id='l2h-4381' class="method">return_ok</tt></b>(</nobr></td>
  <td><var>cookie, request</var>)</td></tr></table></dt>
<dd>
Return boolean value indicating whether cookie should be returned to server.

<p>
<var>cookie</var> is a <tt class="class">cookielib.Cookie</tt> instance.  <var>request</var> is
an object implementing the interface defined by the documentation for
<tt class="method">CookieJar.add_cookie_header()</tt>.
</dl>

<p>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-4382' xml:id='l2h-4382' class="method">domain_return_ok</tt></b>(</nobr></td>
  <td><var>domain, request</var>)</td></tr></table></dt>
<dd>
Return false if cookies should not be returned, given cookie domain.

<p>
This method is an optimization.  It removes the need for checking
every cookie with a particular domain (which might involve reading
many files).  Returning true from <tt class="method">domain_return_ok()</tt> and
<tt class="method">path_return_ok()</tt> leaves all the work to <tt class="method">return_ok()</tt>.

<p>
If <tt class="method">domain_return_ok()</tt> returns true for the cookie domain,
<tt class="method">path_return_ok()</tt> is called for the cookie path.  Otherwise,
<tt class="method">path_return_ok()</tt> and <tt class="method">return_ok()</tt> are never called
for that cookie domain.  If <tt class="method">path_return_ok()</tt> returns true,
<tt class="method">return_ok()</tt> is called with the <tt class="class">Cookie</tt> object itself
for a full check.  Otherwise, <tt class="method">return_ok()</tt> is never called for
that cookie path.

<p>
Note that <tt class="method">domain_return_ok()</tt> is called for every
<em>cookie</em> domain, not just for the <em>request</em> domain.  For
example, the function might be called with both <code>".example.com"</code>
and <code>"www.example.com"</code> if the request domain is
<code>"www.example.com"</code>.  The same goes for
<tt class="method">path_return_ok()</tt>.

<p>
The <var>request</var> argument is as documented for <tt class="method">return_ok()</tt>.
</dl>

<p>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-4383' xml:id='l2h-4383' class="method">path_return_ok</tt></b>(</nobr></td>
  <td><var>path, request</var>)</td></tr></table></dt>
<dd>
Return false if cookies should not be returned, given cookie path.

<p>
See the documentation for <tt class="method">domain_return_ok()</tt>.
</dl>

<p>
In addition to implementing the methods above, implementations of the
<tt class="class">CookiePolicy</tt> interface must also supply the following
attributes, indicating which protocols should be used, and how.  All
of these attributes may be assigned to.

<p>
<dl><dt><b><tt id='l2h-4384' xml:id='l2h-4384' class="member">netscape</tt></b></dt>
<dd>
Implement Netscape protocol.
</dl>
<dl><dt><b><tt id='l2h-4385' xml:id='l2h-4385' class="member">rfc2965</tt></b></dt>
<dd>
Implement RFC 2965 protocol.
</dl>
<dl><dt><b><tt id='l2h-4386' xml:id='l2h-4386' class="member">hide_cookie2</tt></b></dt>
<dd>
Don't add <span class="mailheader">Cookie2:</span> header to requests (the presence of
this header indicates to the server that we understand RFC 2965
cookies).
</dl>

<p>
The most useful way to define a <tt class="class">CookiePolicy</tt> class is by
subclassing from <tt class="class">DefaultCookiePolicy</tt> and overriding some or
all of the methods above.  <tt class="class">CookiePolicy</tt> itself may be used as
a 'null policy' to allow setting and receiving any and all cookies
(this is unlikely to be useful).

<p>

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